This present invention relates generally to the field of alternative fuels and more particularly the conversion of cellular biomass to combustible liquid fuels. Currently much work has been done to generate PHA (poly(3-hydroxyalkanoate)) molecules using recombinant bacteria. Work has been done to isolate and identify genes to produce PHAs for use in medical devices or use as a biodegradable plastic in consumer products. There is also a body of work describing the use of transgenic plants to produce PHAs for use in biodegradable plastics. Moreover, several studies demonstrating PHA production by mixed microbial communities fed a variety of complex feedstocks under a variety of cultivation conditions were performed. The presented invention relates to the use of mixed microbial communities to produce several related bioproducts that are derived from PHA molecules and some of which may be used as a biofuel.
Currently much effort in the alternative fuel sector is directed at making ethanol production an economical alternative to standard gasoline and diesel fuels. Previous work done in this field have been related to the use of biomass to produce ethanol or mixtures of varying alcohol compounds. Some work has been done to derive ethanol from readily available sources such as municipal waste streams. There has also been advancement in the field of novel alternative fuels from renewable sources. This has been done in municipal waste systems where native cellulose has been isolated and then is further converted into varying lengths of hydrocarbons. However, this composition of products is highly variable and depends greatly upon the waste stream obtained from the municipal waste. Currently, waste water treatment plants (WWTPs) recover energy from influent waste streams by generating electricity and heat from by-products of the wastewater treatment methodes by burning biogas. Biogas is a mixed gas byproduct (primarily methane and carbon dioxide) of anaerobic sludge digestion. In addition, production of biodiesel from components of WWTP influent was patented.
This process would allow an alternate method for energy production at WWTPs by production of a mixed liquid biofuel containing low boiling point distillate fraction including alcohol derivatives of alkenoates, hydroxyalkanoates, alkoxyalkanoates, and high boiling point distillate fractions including hydroxy-fatty acids, oligomers of ethyl 3-hydroxyalkanoates, and saturated as well as unsaturated fatty acids. It is generally recognized that the composition of the mixed liquid biofuel will vary with type of alcohol, reaction conditions, microbial community composition, fermentation conditions, and feedstock sources.